YALTAPy_Online is based on YALTAPy, a Python toolbox dedicated to the stability analysis of (possibly fractional) delay systems with commensurate delays given by their transfer function. More details on YALTAPy can be found on its website, https://project.inria.fr/yalta/, its Gitlab repository, https://gitlab.inria.fr/disco/yaltapy-public, and its PyPI page, https://pypi.org/project/yaltapy/. YALTAPy_Online is structured as a Jupyter Notebook and allows one to easily use all of YALTAPy functionalities thanks to its friendly user interface built using interactive widgets from Python's ipywidgets and Qgrid module package. It can be easily run through binder by accessing the link https://mybinder.org/v2/git/https%3A%2F%2Fgitlab.inria.fr%2Fdisco%2FYALTAPy_Online/HEAD?urlpath=tree%2FYALTAPy_Online.ipynb.